Functional Neurological Disorder (FND)
Understanding Functional Neurological Disorder, Conversion Disorder, Diagnosis, and Treatment Options
Written by Gio Arcuri, OT, MSc
Mental Health Occupational Therapist
Course Lecturer, McGill University
Fonder of Clinique Vivago
Neurological symptoms can be frightening—especially when tests come back “normal” but your body still isn’t cooperating. Functional Neurological Disorder (FND), also known as trouble neurologique fonctionnel, is a condition in which real, involuntary neurological symptoms arise from disruptions in how the brain functions, rather than from structural damage. Long misunderstood and often mislabelled, FND is now recognized as a brain-based and treatable condition. This page explains what FND really is, how it’s diagnosed (including its historical link to conversion disorder), and how evidence-based, function-focused care can support recovery.
What is Functional Neurological Disorder (Trouble neurologique fonctionnel)?
Functional Neurological Disorder (FND)—referred to in French as trouble neurologique fonctionnel (TNF)—is a condition in which a person experiences real, involuntary neurological symptoms caused by a disruption in how the brain functions and communicates with the body, rather than by structural damage or disease of the nervous system.
Modern neuroscience describes FND as a disorder of brain network functioning, involving altered integration between movement, sensation, attention, emotion, and regulation systems (Edwards et al., 2012; Stone et al., 2020).
In simple terms:
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Brain structure often appears normal on imaging
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Brain functioning and regulation are disrupted
This explains why symptoms are genuine, disabling, and potentially reversible with functional rehabilitation, rather than through medication or surgery alone.
Common Symptoms of Functional Neurological Disorder
FND can affect nearly any neurological function. Symptoms may fluctuate, improve, or worsen depending on stress, fatigue, sensory load, or environmental demands.
Common symptoms include:
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Limb weakness or paralysis
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Tremors or involuntary movements
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Difficulty walking or balance problems
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Non-epileptic (functional) seizures
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Sensory changes (numbness, tingling, visual disturbances)
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Speech or swallowing difficulties
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Fatigue and cognitive overload
These symptoms are not consciously produced. Research suggests they arise from altered attention, prediction, and motor control processes in the brain (Voon et al., 2016).
For many individuals, symptoms emerge or intensify during periods of burnout, illness, emotional overload, or major life transitions. For some, this intersects with broader questions of sensory processing, regulation, and identity, which is why FND is sometimes discussed alongside neurodiversity.
(Internal link opportunity: “What is neurodiversity?”)
Functional vs Structural Neurological Conditions
A core concept in understanding FND is the distinction between structural and functional neurological conditions.
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Structural neurological disorders (e.g., stroke, multiple sclerosis, Parkinson’s disease) involve identifiable damage or disease processes in the nervous system.
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Functional neurological disorder involves disrupted coordination, regulation, and signaling, despite intact structures.
Functional neuroimaging studies show altered connectivity between motor, emotional, and attentional networks in people with FND, supporting this distinction (Perez et al., 2015; McWhirter et al., 2020).
This difference does not make symptoms less real.
It clarifies why treatment focuses on retraining function, rather than “finding damage.”
DSM-5 Diagnostic Criteria for Functional Neurological Disorder
According to the DSM-5, Functional Neurological Disorder (also termed Functional Neurological Symptom Disorder) is diagnosed using positive clinical criteria, not by exclusion alone.
DSM-5 Criteria
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One or more symptoms of altered voluntary motor or sensory function
Examples include weakness, tremor, abnormal movements, gait disturbance, seizures, or sensory loss.
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Clinical evidence of incompatibility
The symptom presentation is inconsistent with recognized neurological diseases and may vary across tasks or contexts.
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The symptom is not better explained by another medical or mental disorder
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The symptom causes significant distress or functional impairment
Affecting daily life, work, education, or relationships.
Importantly, DSM-5 removed the requirement to identify a psychological stressor, reflecting current understanding that FND is a brain-based functional condition (American Psychiatric Association, 2013; Stone et al., 2020).
Is Conversion Disorder Part of Functional Neurological Disorder?
Yes. Conversion disorder is the historical term for what is now clinically referred to as Functional Neurological Disorder.
In earlier diagnostic systems, conversion disorder described neurological symptoms—such as paralysis, blindness, or seizures—that were thought to result from psychological conflict being “converted” into physical symptoms. This concept originates in early psychodynamic theory.
Today, this understanding has evolved.
In DSM-5, the diagnosis previously known as conversion disorder is now formally named:
Functional Neurological Symptom Disorder (Functional Neurological Disorder)
This change reflects advances in neuroscience showing that symptoms are linked to functional changes in brain networks, rather than symbolic psychological conversion alone.
How Modern Medicine Understands “Conversion” Today
While the historical conversion model emphasized psychological causation, contemporary research shows that:
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Symptoms are real and involuntary
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Brain function—particularly attention, emotion, and motor prediction—is altered
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Psychological stress may be a contributing factor, but is not required for diagnosis
In other words, what was once called “conversion” is now understood as a disruption in brain–body communication and regulation (Edwards et al., 2012; Pick et al., 2019).
This shift:
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Reduces stigma
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Avoids implying symptoms are “all psychological”
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Supports functional, rehabilitation-based treatment
When Is the Term “Conversion Disorder” Still Used?
The term conversion disorder may still appear:
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In older medical records
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In insurance documentation
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In some psychiatric or psychodynamic contexts
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In patient histories predating DSM-5
Some individuals also find the term meaningful when their symptoms clearly emerged during periods of trauma, emotional overload, or identity conflict.
However, most contemporary clinicians now prefer Functional Neurological Disorder, as it aligns better with current neuroscience and supports a clearer path to recovery.
What Causes Functional Neurological Disorder?
FND is best understood through a biopsychosocial and neurofunctional model, integrating brain physiology, lived experience, and environmental demands.
Contributing factors may include:
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Nervous system dysregulation
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Prior injury, illness, or medical trauma
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Chronic stress or burnout
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Prolonged threat or shutdown states
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Neurodivergent sensory or cognitive profiles
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Learned movement or avoidance patterns
Rather than a failure of willpower, symptoms reflect maladaptive but reversible brain patterns (Edwards et al., 2012; Pick et al., 2019).
This understanding closely aligns with occupational and functional models of health that focus on how people function in daily life, not solely on diagnoses.
(Internal link opportunity: “What is occupational therapy?”)
Why Reassurance or Medication Alone Is Often Insufficient
Education and reassurance are essential first steps, but research shows they are rarely sufficient on their own (Nielsen et al., 2017).
Because FND affects daily functioning, effective care must address:
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Movement and coordination
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Energy management and fatigue
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Emotional and sensory regulation
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Attention and pacing
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Identity, safety, and self-trust
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Participation in work, school, and relationships
This functional lens is central to occupational therapy-led approaches, which target real-life participation rather than symptoms in isolation.
(Internal link opportunity: “What is occupational therapy?”)
Evidence-Based Treatment for Functional Neurological Disorder
Clinical guidelines and systematic reviews support active, interdisciplinary treatment for FND (Stone et al., 2020; Nielsen et al., 2017).
Core Treatment Components
Functional rehabilitation
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Occupational therapy
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Physiotherapy
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Task-specific retraining
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Graded exposure to avoided activities
Psychological interventions
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Trauma-informed psychotherapy
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Cognitive-behavioral approaches
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EMDR or other trauma-focused therapies when indicated
Nervous system regulation
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Education about brain–body functioning
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Sensory modulation strategies
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Pacing and fatigue management
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Stress physiology and regulation tools
The goal is functional recovery and autonomy, not simply symptom reduction.
Intensive Outpatient Programming for Functional Neurological Disorder
For many individuals, weekly therapy is not sufficient, especially when symptoms are longstanding, complex, or severely disruptive.
Research supports intensive, coordinated rehabilitation, allowing repetition, consistency, and real-world practice (Demartini et al., 2014; Nielsen et al., 2017).
This is where intensive outpatient programs play a critical role.
(Internal link opportunity: “Intensive programs at Vivago”)
Intensive and Semi-Intensive Outpatient Programs at Vivago
At Clinique Vivago, we offer intensive and semi-intensive outpatient rehabilitation programs for people experiencing functional and neurofunctional conditions, including Functional Neurological Disorder.
Our programs include:
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Occupational therapy-led functional rehabilitation
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Psychological care that is trauma-informed and identity-aware
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Nervous system regulation and pacing
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Real-life functional practice beyond the therapy room
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Flexible intensity without hospitalization
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Access without requiring a formal diagnosis
Focus areas include:
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Restoring daily routines
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Improving mobility and coordination
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Reducing symptom-driven avoidance
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Rebuilding autonomy and confidence
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Supporting return to work, school, or meaningful roles
This model emphasizes functional recovery, dignity, and agency, rather than a diagnosis-first approach.
(Internal link opportunity: “Intensive programs at Vivago”)
Living With Functional Neurological Disorder
Functional Neurological Disorder is real, common, and treatable.
With appropriate, function-focused care:
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Symptoms can improve
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Daily functioning can be restored
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Trust in the body and nervous system can return
FND does not mean “nothing is wrong.”
It means the nervous system needs support, retraining, and safety.
Is Conversion Disorder Part of Functional Neurological Disorder?
Yes. Conversion disorder is the historical term for what is now clinically referred to as Functional Neurological Disorder (FND).
In earlier diagnostic systems, conversion disorder described neurological symptoms—such as paralysis, blindness, or seizures—that were thought to arise from psychological conflict being “converted” into physical symptoms. This concept dates back to Freud and early psychodynamic theory.
Today, this understanding has evolved significantly.
In the DSM-5, the diagnosis previously known as conversion disorder is now formally named:
Functional Neurological Symptom Disorder (Functional Neurological Disorder)
This change reflects advances in neuroscience showing that symptoms are linked to altered brain network functioning, not symbolic psychological conversion alone.
How Modern Medicine Understands “Conversion” Today
While the term conversion disorder emphasized psychological causation, modern models recognize that:
-
Symptoms are real and involuntary
-
Brain imaging and neurophysiology show functional changes in attention, motor control, emotion, and prediction networks
-
Psychological stress may be a contributing factor, but is not required for diagnosis
In other words, what was once framed as “conversion” is now understood as a disruption in brain–body communication and regulation.
This shift is one of the reasons DSM-5:
-
Removed the requirement to identify a psychological stressor
-
Focused on positive neurological signs and functional impairment
-
Moved away from implying that symptoms are “caused by emotions alone”
When Is the Term “Conversion Disorder” Still Used?
The term conversion disorder may still appear:
-
In older medical records
-
In insurance documentation
-
In some psychodynamic or psychiatric contexts
-
In patient histories where the diagnosis predates DSM-5
Some individuals may also identify with the term because it reflects how their symptoms emerged during periods of trauma, emotional overload, or life disruption.
However, most contemporary clinicians now prefer Functional Neurological Disorder, as it:
-
Reduces stigma
-
Aligns with current neuroscience
-
Supports functional, rehabilitation-based treatment
Psychological Factors: Part of the Picture, Not the Whole Story
Psychological processes—such as trauma, chronic stress, emotional suppression, or identity conflict—can absolutely play a role for some people with FND.
This is where the historical concept of conversion still offers insight, particularly when:
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Symptoms emerge after overwhelming experiences
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The nervous system has learned to remain in threat or shutdown states
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Expression through the body becomes the brain’s way of coping
At the same time, many people with FND:
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Do not identify a specific trauma
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Are neurodivergent and experience chronic sensory or cognitive overload
(Internal link opportunity: “What is neurodiversity?”)
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Develop symptoms following illness, injury, or burnout rather than emotional conflict
Modern care holds both realities at once, without reducing symptoms to psychology alone.
Why This Distinction Matters for Treatment
Understanding the evolution from conversion disorder to Functional Neurological Disorder directly impacts care.
If symptoms are viewed as:
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“Psychological only” → people may be told to “just talk about it”
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“Structural disease” → people may undergo unnecessary tests or feel hopeless
When symptoms are understood as functional and reversible, treatment can focus on:
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Retraining movement and coordination
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Regulating the nervous system
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Restoring daily functioning and roles
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Addressing psychological factors when relevant, not by default
This is where occupational therapy plays a central role, by targeting how symptoms affect real-life participation.
(Internal link opportunity: “What is occupational therapy?”)
Conversion Disorder, FND, and Intensive Treatment
For individuals whose symptoms are longstanding, complex, or highly disruptive, intensive outpatient rehabilitation is often more effective than weekly therapy alone.
This is especially true when symptoms:
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Are reinforced by avoidance or fear
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Fluctuate with stress and fatigue
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Affect multiple areas of daily functioning
Modern intensive programs integrate:
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Functional rehabilitation
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Nervous system regulation
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Psychological care without pathologizing
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Real-life practice and repetition
This approach moves beyond the outdated conversion model toward functional recovery and autonomy.
(Internal link opportunity: “Intensive programs at Vivago”)
Key Takeaway
Conversion disorder is not “wrong”—it is incomplete.
Functional Neurological Disorder reflects:
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Current neuroscience
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Reduced stigma
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A clearer path to treatment
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A focus on what truly matters: function, dignity, and recovery
References
American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.).
Edwards, M. J., Adams, R. A., Brown, H., Pareés, I., & Friston, K. J. (2012). A Bayesian account of “hysteria.” Brain, 135(11), 3495–3512.
Perez, D. L., et al. (2015). Functional neuroimaging in functional neurological disorder. Journal of Neurology, Neurosurgery & Psychiatry, 86(6), 613–620.
Pick, S., et al. (2019). Functional neurological disorder: An update for clinicians. Journal of Neurology, 266, 1–13.
Stone, J., et al. (2020). Functional neurological disorder: Diagnosis and treatment. The Lancet Neurology, 19(2), 141–152.
Voon, V., et al. (2016). Neurobiology of functional neurological disorders. Current Opinion in Neurology, 29(4), 442–447.
Nielsen, G., et al. (2017). Physiotherapy for functional motor disorders. Journal of Neurology, 264(8), 1627–1638.
Demartini, B., et al. (2014). Multidisciplinary treatment for functional neurological symptoms. Journal of Neurology, 261(12), 2370–2377.
FAQ: Functional Neurological Disorder (FND)
1. Is Functional Neurological Disorder the same as conversion disorder?
Yes. Conversion disorder is the historical term for what is now called Functional Neurological Disorder (FND). Modern medicine uses the term FND to reflect current neuroscience, which shows that symptoms arise from changes in brain functioning rather than from psychological conflict alone.
2. Are symptoms real even if medical tests are normal?
Yes. Symptoms in FND are real, involuntary, and can be very disabling, even when scans or tests appear normal. FND affects how the brain sends and regulates signals, not the brain’s structure, which is why standard tests may not show damage.
3. Is Functional Neurological Disorder caused by anxiety or trauma?
Not always. Psychological factors such as stress or trauma can play a role for some people, but they are not required for a diagnosis of FND. Many individuals develop symptoms after illness, injury, burnout, or prolonged nervous system overload.
4. Can Functional Neurological Disorder improve or go away?
Yes. FND is treatable, and many people experience significant improvement with appropriate, function-focused care. Recovery often involves retraining movement, regulating the nervous system, and restoring daily functioning rather than focusing only on symptom reduction.
5. Why is occupational therapy important in treating FND?
Occupational therapy focuses on how symptoms affect daily life—such as work, school, routines, and relationships. In FND, occupational therapists help retrain functional movements, manage fatigue and sensory overload, and support a return to meaningful activities.
(Internal link opportunity: “What is occupational therapy?”)
6. When are intensive outpatient programs recommended for FND?
Intensive outpatient programs are often helpful when symptoms are longstanding, complex, or significantly impact daily functioning. These programs provide consistent, coordinated care that supports nervous system regulation and functional recovery.
(Internal link opportunity: “Intensive programs at Vivago”)